At least 3 dead after helicopter crashes in western Norway

He calls this "the worst helicopter accident we've ever had over land"

The site has been cordoned off and investigators will arrive Tuesday

(CNN) -- At least three people died after their helicopter crashed late Monday in western Norway, authorities said.

Norwegian police spokesman Gry Benedicte Halseth said in a statement that the number of people on board has not been established. But Gudmund Taraldsen, an officer with the Norwegian Civil Aviation Authority, told CNN that there were five people total on the helicopter when it went down, meaning two people are still unaccounted for.

The helicopter was hired by house builders to fly up into the Norwegian mountains, Halseth said. The aircraft -- an Aerospatiale 350 -- crashed before 8 p.m. Monday in a remote locale at the bottom of the Hardanger fjord, east of Bergen, Taraldsen said.

"I don't have any information about the cause of the accident, but there are very poor weather conditions at the site," the aviation authority officer said.

This is the worst helicopter accident we have ever had over land.--Gudmund Taraldsen from the Norwegian Civil Aviation Authority.